Each day a question becomes a machine you can run. Every machine proves one true number.
No. 6
$66.67
With $5,000 cash at 2× leverage and a 25% maintenance margin, the call hits at $66.67 — 100 shares, a $5,000 loan, and equity of $1,667 at the call.
Big ideaA margin call is not a prediction — it is a price: the moment your equity falls to the maintenance margin, the broker sells, whether you agree or not.
Break it1.5–3× leverage, 10–30% maintenance margin
No. 5
4.85 L a flush
A WaterSense toilet uses at most 1.28 gallons (4.85 L) a flush, and the fill valve puts all of it back (3.64 L into the tank, 1.21 L down the refill tube to the bowl) until the float shuts it off at the fill line.
Big ideaThe float decides how much, the pipe only decides how fast, so every flush refills the same 4.85 L.
Break itfill-valve flow 1.5–6.0 gal/min (0.5 steps): refill time = 4.85 L ÷ flow, 51.2 s down to 12.8 s
No. 4
$8.56
Three ±10% round trips: the index ends at $97.03, the 2x fund at $88.47. It lags by $8.56.
Each round trip costs 1x 1% and 2x 4%: four times the drag.
Big ideaLeverage resets daily, so a round trip that leaves the index nearly flat still grinds the 2x fund down.
Break itdaily swing 5–20%
No. 3
100°C
At 100°C, steam runs down a tube and bends a bimetallic strip until it trips the switch. No timer.
Six steps from Fill to CLICK, with a cutaway of the steam tube and the strip.
Big ideaSteam, not a timer, switches the kettle off: hot steam bends the strip, and the strip trips the switch.
No. 2
$9.91
A year of ±10% days leaves the index at exactly $100.00 and the 2x daily-reset fund at $9.91.
One up-down pair costs the 2x fund 1.82%; on a calm +1% trend it beats 2× the gain ($121.90 vs $120.92).
Big ideaA loss shrinks the base, so the same rebound pays back less, and 2x feels it twice.
Break itdaily swing 0–10%, leverage 1–3x
No. 1
Month 216
At 7% a year, month 216 (year 18) is when the interest passes the $21,600 you put in.
By year 30: $36,000 in, $86,709 of interest, 2.4× your own money.
Big ideaInterest earns interest, so the gold grows faster every year.
Break itexample rate, 0–12%